1. Field of the Invention
The present invention relates to a mobile unit support system and mobile unit detection device and a system capable of transmitting information by transmitting and receiving signals between a plurality of modules installed at different positions.
2. Related Art of the Invention
For a practical and optimum sophisticated road traffic system to be realized, the following five factors are considered crucial.
1. Possibility of measuring the following distance of vehicles PA0 2. Possibility of drive support PA0 3. Possibility of automatic drive PA0 4. Possibility of communication from the vehicle PA0 5. Possibility of inter-vehicle communication
The situation of the prior art for each of the above-mentioned five factors will be explained.
As to a vehicle for which the following distance is measurable as in (1) above, though not currently available, provision of a laser measuring instrument, an ultrasonic measuring instrument or the like would make it possible to measure the following distance. The measurement of the following distance is indispensable for the factors (2) and (3).
As to the items (2) and (3) above relating to the drive support and the automatic drive, respectively, there is not any means currently available. Research is under way in each organization for a drive support or an automatic drive system with a computer mounted on a vehicle using a method unique to each organization. Details of the research, however, are unknown.
The use of a portable telephone or the like can realize the factors (4) and (5). Also, the radio or the like equipment permits acquisition of information on traffic congestion or the like.
The above-mentioned methods, however, require realization of the five factors separately from each other, and it is impossible to realize an overall efficient road traffic system.
Especially, the factor (4) has no relation with the factors (1) to (3), and it seem that they can be processed independently of each other. If information to be communicated is of the type used with a navigator, however, the factor (4) may be related to the factors (1) to (3). It is not efficient, therefore, to realize the above-mentioned five factor independently of each other but an overall integrated system is desirably built up. By doing so, the road conditions can be accurately grasped, and the information used with the navigator can be generated based on the road conditions, thereby making it possible to supply information much more useful than the information obtained from the CD ROM or the like.
Also, in the case where a vehicle performs a communication, or especially, in the case where information on automatic drive or the like is transmitted or received between the vehicle and other stations, a multiplicity of vehicles running on a road undesirably transmit a high-output radio wave.
Also, the conventional method of producing information on traffic congestion or the like has the problem that since the number and places of installation of automotive vehicle detection units are limited, the movement conditions of individual automotive vehicles cannot be grasped, and therefore it is impossible to acquire detailed road situations including accidents and traffic congestion. For this reason, the road situations within a small area can be known only in a range visible by eyes, thereby making it impossible to know the road situations out of sight.